BBA= trim off old worthless(to the plant anyway) leaves.
you may need to wait a bit for the new growth to fill in so you can trim with something left over, 1-2 weeks etc.
In the meantime, some folks will spot treat with H2O2. Do not add more than 10 mls per 10 Gal worth of aquarium at any one time.
After 3-6 weeks, the BBA will slowly go away and you can trim it out.
Some use SAE's(a fish) to gnaw the BBA. They get lazy and bully other fish later as they get old and not longer eat BBA.
Mostly just keeping on top 0f things and trimming, good CO2, good light, ferts are pretty easy relatively speaking, tap water sounds perfect, you may only need a little Mg. Otherwise KNO3, KH2PO4, and Trace mix(MgSO4 can be added to this) eg CMS+B.
IME, diffusers clog and change the dosing of CO2.
They need cleaned routinely and maintained.
Good current for the surface, some rippling etc.........= key to making sure there's ample O2.
Fish Respiration MUST include both CO2 and O2 levels, not just CO2.
If you have high CO2 and low O2 in the aquarium= least amount of wiggle room with dosing CO2 and stressing fish. High O2 and high CO2= decent for fish, great for plants, both are happy. My fish and shrimp bred in every tank I own, so they are doing pretty good.
You will use more CO2 and degas more, but you gain more O2, thus can use more CO2. I have about 55-60ppm on average for my aquariums. But I have excellent filtration(Wet/dry filters, surface skimming etc) and excellent current.
Odd thing is, Dupla made a big deal about wet/drys and good current in the 1980's, few listened.
To date, I've never seen a confirmed case of Ca++ deficient aquarium plant.
CO2 looks a lot like that claim.
And I've seen more CO2 issues that I can shake a stick at, I'm not saying 100% of the time..........but 99.99, okay 99.999% of the time, it'll be something else like CO2.
also remember this about cO2 measurement, the pH/KH chart will NEVER tell you that you have more CO2 than you think, only less.
So say the chart says I have 40 ppm. I might have 40ppm or less, I CANNOT have more than 40ppm however.
Now some folks measure and the chart says they have 200-300ppm, plants and fish are fine.
The chart is obviously incorrect and has over estimated the actual CO2, which is likely in the 30-50ppm rnge for many of these folks.
So the chart will underestimate the actual value in all cases or be close to the actually value.
This makes many think they have 30 ppm, when they may only have 10ppm and have algae.
Or they rush and adjust the CO2 way to fast and then leave for work to come home to gasping or dead fish in the tank.